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@@ -0,0 +1,211 @@
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+package usbcapture
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+
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+import (
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+ "bufio"
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+ "fmt"
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+ "log"
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+ "net/http"
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+ "os"
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+ "os/exec"
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+ "regexp"
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+ "strings"
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+
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+ "github.com/gorilla/websocket"
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+)
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+
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+// upgrader is used to upgrade HTTP connections to WebSocket connections
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+var upgrader = websocket.Upgrader{
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+ ReadBufferSize: 1024,
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+ WriteBufferSize: 1024,
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+ CheckOrigin: func(r *http.Request) bool {
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+ return true
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+ },
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+}
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+
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+// ListCaptureDevices lists all available audio capture devices in the /dev/snd directory.
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+func ListCaptureDevices() ([]string, error) {
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+ files, err := os.ReadDir("/dev/snd")
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+ if err != nil {
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+ return nil, fmt.Errorf("failed to read /dev/snd: %w", err)
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+ }
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+
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+ var captureDevs []string
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+ for _, file := range files {
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+ name := file.Name()
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+ if strings.HasPrefix(name, "pcm") && strings.HasSuffix(name, "c") {
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+ fullPath := "/dev/snd/" + name
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+ captureDevs = append(captureDevs, fullPath)
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+ }
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+ }
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+
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+ return captureDevs, nil
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+}
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+
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+// FindHDMICaptureCard searches for an HDMI capture card using the `arecord -l` command.
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+func FindHDMICapturePCMPath() (string, error) {
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+ out, err := exec.Command("arecord", "-l").Output()
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+ if err != nil {
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+ return "", fmt.Errorf("arecord -l failed: %w", err)
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+ }
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+
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+ lines := strings.Split(string(out), "\n")
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+ for _, line := range lines {
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+ lower := strings.ToLower(line)
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+ if strings.Contains(lower, "ms2109") || strings.Contains(lower, "ms2130") {
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+ // Example line:
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+ // card 1: MS2109 [MS2109], device 0: USB Audio [USB Audio]
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+ parts := strings.Fields(line)
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+ var cardNum, devNum string
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+ for i := range parts {
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+ if parts[i] == "card" && i+1 < len(parts) {
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+ cardNum = parts[i+1][:1] // "1"
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+ }
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+ if parts[i] == "device" && i+1 < len(parts) {
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+ devNum = strings.TrimSuffix(parts[i+1], ":") // "0"
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+ }
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+ }
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+
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+ if cardNum != "" && devNum != "" {
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+ return fmt.Sprintf("/dev/snd/pcmC%vD%vc", cardNum, devNum), nil
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+ }
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+ }
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+ }
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+
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+ return "", fmt.Errorf("no HDMI capture card found")
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+}
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+
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+// Convert a PCM device name to a hardware device name.
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+// Example: "pcmC1D0c" -> "hw:1,0"
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+func pcmDeviceToHW(dev string) (string, error) {
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+ // Regex to extract card and device numbers
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+ re := regexp.MustCompile(`pcmC(\d+)D(\d+)[cp]`)
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+ matches := re.FindStringSubmatch(dev)
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+ if len(matches) < 3 {
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+ return "", fmt.Errorf("invalid device format")
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+ }
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+ card := matches[1]
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+ device := matches[2]
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+ return fmt.Sprintf("hw:%s,%s", card, device), nil
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+}
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+
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+func GetDefaultAudioConfig() *AudioConfig {
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+ return &AudioConfig{
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+ SampleRate: 48000,
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+ Channels: 2,
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+ BytesPerSample: 2, // 16-bit
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+ FrameSize: 1920, // 1920 samples per frame = 40ms @ 48kHz
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+ }
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+}
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+
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+// AudioStreamingHandler handles incoming WebSocket connections for audio streaming.
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+func (i Instance) AudioStreamingHandler(w http.ResponseWriter, r *http.Request) {
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+ conn, err := upgrader.Upgrade(w, r, nil)
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+ if err != nil {
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+ log.Println("Failed to upgrade to websocket:", err)
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+ return
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+ }
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+ defer conn.Close()
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+
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+ if i.audiostopchan != nil {
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+ //Another instance already running
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+ log.Println("Audio pipe already running, stopping previous instance")
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+ i.audiostopchan <- true
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+ }
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+
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+ //Get the capture card audio input
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+ pcmdev, err := FindHDMICapturePCMPath()
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+ if err != nil {
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+ log.Println("Failed to find HDMI capture PCM path:", err)
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+ http.Error(w, "Internal Server Error", http.StatusInternalServerError)
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+ return
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+ }
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+
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+ log.Println("Found HDMI capture PCM path:", pcmdev)
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+
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+ // Convert PCM device to hardware device name
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+ hwdev, err := pcmDeviceToHW(pcmdev)
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+ if err != nil {
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+ log.Println("Failed to convert PCM device to hardware device:", err)
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+ http.Error(w, "Internal Server Error", http.StatusInternalServerError)
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+ return
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+ }
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+
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+ log.Println("Using hardware device:", hwdev)
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+
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+ // Create a buffered reader to read audio data
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+ i.audiostopchan = make(chan bool, 1)
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+ log.Println("Starting audio pipe with arecord...")
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+
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+ // Start arecord with 24kHz, 16-bit, stereo
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+ cmd := exec.Command("arecord",
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+ "-f", "S16_LE", // Format: 16-bit little-endian
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+ "-r", fmt.Sprint(i.Config.AudioConfig.SampleRate),
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+ "-c", fmt.Sprint(i.Config.AudioConfig.Channels),
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+ "-D", hwdev, // Use the hardware device
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+ )
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+
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+ stdout, err := cmd.StdoutPipe()
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+ if err != nil {
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+ log.Println("Failed to get arecord stdout pipe:", err)
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+ http.Error(w, "Internal Server Error", http.StatusInternalServerError)
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+ return
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+ }
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+
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+ if err := cmd.Start(); err != nil {
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+ log.Println("Failed to start arecord:", err)
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+ http.Error(w, "Internal Server Error", http.StatusInternalServerError)
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+ return
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+ }
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+
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+ reader := bufio.NewReader(stdout)
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+ bufferSize := i.Config.AudioConfig.FrameSize * i.Config.AudioConfig.Channels * i.Config.AudioConfig.BytesPerSample
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+ log.Printf("Buffer size: %d bytes (FrameSize: %d, Channels: %d, BytesPerSample: %d)",
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+ bufferSize, i.Config.AudioConfig.FrameSize, i.Config.AudioConfig.Channels, i.Config.AudioConfig.BytesPerSample)
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+ buf := make([]byte, bufferSize*2)
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+
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+ // Start a goroutine to handle WebSocket messages
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+ log.Println("Listening for WebSocket messages...")
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+ go func() {
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+ _, msg, err := conn.ReadMessage()
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+ if err == nil {
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+ if string(msg) == "exit" {
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+ log.Println("Received exit command from client")
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+ i.audiostopchan <- true // Signal to stop the audio pipe
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+ return
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+ }
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+ }
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+ }()
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+
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+ log.Println("Starting audio capture loop...")
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+ for {
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+ select {
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+ case <-i.audiostopchan:
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+ log.Println("Audio pipe stopped")
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+ goto DONE
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+ default:
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+ n, err := reader.Read(buf)
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+ if err != nil {
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+ log.Println("Read error:", err)
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+ goto DONE
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+ }
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+
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+ if n == 0 {
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+ continue
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+ }
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+
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+ //log.Println("Read bytes:", n, "size of buffer:", len(buf))
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+ //Send only the bytes read to WebSocket
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+ err = conn.WriteMessage(websocket.BinaryMessage, buf[:n])
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+ if err != nil {
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+ log.Println("WebSocket send error:", err)
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+ goto DONE
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+ }
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+ }
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+ }
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+
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+DONE:
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+
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+ i.audiostopchan <- true // Signal to stop the audio pipe
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+ cmd.Process.Kill()
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+ log.Println("Audio pipe finished")
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+}
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TC